Re: [Amel Yacht Owners] Re: Watermaker Dead

Ian Shepherd

Hi Gary,

Thanks for your thoughts. I am careful with o-rings and do clean the groove
thoroughly before smearing them with silicone grease. Amel say that Vaseline
will do. Being petroleum based, I am not so sure. I certainly use silicone
grease on all my diving seals. I know it's safer when in contact with high
pressure air than grease. I would appreciate your thoughts on silicone
versus Vaseline on 0-rings. What I have not previously done is to run a pick
around under the seal. A good tip. I do however look at them carefully with
a magnifying glass before pushing the bobbin back into the end cap.

The latest failure had never been disturbed by me, being under the curved
end cap bracket that carries the hose connection. There did appear to be
some erosion of the lower seal in line with where the end cap material had
been washed away. Whether this was from escaping water or a badly fitted
seal is a matter of conjecture.

I doubt if my HP gauge is poorly calibrated else the flow rate would be off
the top of the sight tube. I adjust the pressure so that I achieve 160 l/h
(in warm water). The needle is usually about one third up the green band on
the HP gauge.



-------Original Message-------

From: amelliahona
Date: 19/09/2007 04:28:14
Subject: [Amel Yacht Owners] Re: Watermaker Dead

Hi Ian:

Thanks for your input. Regarding:

"To be exact, yet another leaking end cap, this time at the hose
connection end. Water had got pass the two 1.5mm x 9mm o-rings
and eroded the nylon, creating a serious leak. This was my 5th end
cap failure in just over 200 hours of operation! My end caps are
white. Has anyone else had a similar problem? Amel say that it is
very rare! I don't believe them."

I am not sure why you are having such leakage problems.

I have had no leaks from my end caps. My first set of end caps where
white plastic (?nylon) (see photo's in the photo section where I am
trying to remove the white end caps). They looked pristine when
removed during the replacement of my membranes that failed at
the 185 hour mark. I replaced the end caps anyway at the suggestion
of Amel's Olivier Beatue at that time (185 hours). I ordered the end
caps from Dessalator and received the black caps depicted in the
photo's section. I currently only have about 240 hours on the water
maker but I am still leak free.

Just a thought. Could it be that you got a batch of poor guality
o-rings? This might explain the recurrent leaks. The other
possibility is that the o-rings aren't seating well when installed.
Perhaps they have a twist in them?

When I install aircraft o-rings I lube them with a silicone lube, then
after meticulous cleaning of the o-ring groove, I roll the o-ring
into the groove. I then use a plastic pic to to lift a point on the
o-ring circumference and run the pic around the circumference
a couple of times to insure there are no twists.

Is it possible that your high pressure gauge is out of calibration
and the system is being over pressurized? Not sure if any of
these things are the actual cause but it certainly seems that you
are suffering from a higher failure rate than I have experienced
or heard about.

Regards, Gary

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